How can I make this arm accessory?
You can paint the holes with transparency. Basically, as you already did.
Bake the normal map from the Multires and then texture the accessory.
Use the alpha channel (or create a separate mask image) for Alpha slot of the Principled BSDF (or use a Transparent BDSF and a MixShader). Add some metal rings. That's it.
I had made something similar. Looks like this:
Low-poly mesh with rings (low poly circles + Solidify and Subdivision modifiers)

Textured with transparency (no baked normal map yet)

You can even pull a ribbon through the eyelets :-)

The ribbon is just flat plane with a Solidify and Subdivision modifier. In fact, it's not one part but several &quot;V&quot; parts.